Choice of the Optimal Surgical Approach for Skull Base Chordomas

Despite the tremendous improvement in adjuvant therapy, surgical radical removal is the main tool in the management of skull base chordomas. Several principles in the management of this disease must be understood.

13.1.1 Rule of 10

The tumor is mainly extradural; therefore, an extradural route should be used.
Explain to the patient that sometimes more than one surgical procedure is needed to obtain a radical removal.
The more that is removed the better will be the results and the effectiveness of adjuvant treatment.
The first time is the best time.
“Radical removal” means removal of soft tissue and maximal resection of adjacent bone, which is not related with higher morbidity.
The endoscopic techniques should be use in all cases to optimize the view in the hidden corners, not only in the transnasal approach.
Neuronavigation will help to find islands of bony invasion that may be hidden in the surgical field but depicted in the preoperative computed tomography (CT) scan or magnetic resonance imaging (MRI).
Preoperative CT with thin-cut bony window and MRI are crucial for surgical planning.
Recurrence time is directly related to the first attempt at removal, histology, and cytogenetic features.
Follow the patient very closely. Be aware of any signs of recurrence, and a new treatment may be planned.

13.1.2 Commitment

Skull base surgery demands complete dedication and extensive training. The surgeon must master the technique and the enfolded anatomy in its totality. Treating patients with skull base chordomas demands a highly trained multidisciplinary team, which knows that the natural history of the disease requires their full commitment to the patient and their family, as they will be followed through a lifetime.

13.1.3 Principles

Surgical treatment represents a crucial step in the management of skull base chordomas, and the literature has demonstrated good tumor control when surgery is followed by high-dose proton–photon radiation therapy. ¹^,²^,³^,⁴^,⁵^,⁶^,⁷^,⁸^,⁹^,¹⁰^,¹¹ Although aggressive tumor removal has been associated with higher morbidity and mortality rates, ¹² Colli and Al-Mefty demonstrated that the proportions of patients with surgery-related complications who had undergone radical and subtotal resection were not significantly different. ⁴ Therefore, the goal of surgical treatment should be maximum tumor resection, with higher chances of success at first surgery.

13.2 Tumor Location

13.2.1 Origin and Extension

Chordomas are believed to arise from remnants of the notochord; therefore, they can occur anywhere along the neuroaxis. ³ The present literature points to a similar incidence in the skull base, sacrum, and mobile spine. ¹³^,¹⁴ Typically, skull base chordomas arise in the midline, at the spheno-occipital synchondrosis, but lateral extension is a common finding. Such tumors frequently grow into multiples directions and extend through different compartments, intra- and extracranially. ²^,⁴^,¹¹ Common sites of extension includes the sellar region (23–60% of cases), prepontine space (36–48% of cases), and nasopharynx (10–25% of cases). ¹^,¹⁵^,¹⁶ Extension to the middle fossa (32.1% of cases) and posterior fossa (78.5% of cases) are frequent as well. ¹⁶ Involvement of the occipital condyles is better identified on CT scanning and frequently leads to advanced bone erosion and cervical instability. ¹⁷ The deep location and pattern of spread of chordomas make the access to these lesions a laborious task; however, many approaches lead to the clival areal from an anterior, lateral, or posterior view. ³ The acknowledgment of the sites of extension of the tumor is the underlying condition when choosing the optimal approach, and often two or more procedures are necessary to achieve a radical removal. ⁴

13.2.2 Classification

Al-Mefty and Borba proposed a surgical classification based on the anatomical extension of the tumor. Type I are lesions restricted to a solitary anatomical area (e.g., lower clivus or sphenoid sinus). Type II tumors extend to two or more contiguous areas of the skull base and whose radical removal can be achieved through a single skull base approach. Type III are lesions that extend to multiple compartments of the skull base and require two or more skull base procedures to achieve maximum surgical removal. ¹

13.3 Surgical Armamentarium

13.3.1 Preoperative Studies

MRI is the choice for analyzing the relationships of the tumor with soft tissue as neural structures; however, it should be complemented with thin-cut CT scanning, especially the bony window, which is the best study to identify bone erosion. ³^,¹⁷

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